practical quiz 2.debuggingreport.txt

CMU SSD3 课程完整答案（除EXAM）

---------------------------------------------------------------------------
Bug #1

Description of the bug:

	The variable "enumberOfC" increases twice while the variable "numberOfG" is never read.

Lines of source code that contain the bug:

	if (nucleotide == 'A') {
		numberOfA++;
	} else if (nucleotide == 'T') {
		numberOfT++;
	} else if (nucleotide == 'C') {
		numberOfC++;
	} else if (nucleotide == 'C') {
		numberOfC++;
	}

Lines of the fixed code:
	
	if (nucleotide == 'A') {
		numberOfA++;
	} else if (nucleotide == 'T') {
		numberOfT++;
	} else if (nucleotide == 'C') {
		numberOfC++;
	} else if (nucleotide == 'G') {
		numberOfG++;
	}

---------------------------------------------------------------------------
Bug #2

Description of the bug:
	
	The variables containing the number of nucleotides are overrided by local variables in the method "countNucleotides()".

Lines of source code that contain the bug:

	int numberOfA = 0;
	int numberOfT = 0;
	int numberOfC = 0;
	int numberOfG = 0;

Lines of the fixed code:

	numberOfA = 0;
	numberOfT = 0;
	numberOfC = 0;
	numberOfG = 0;

---------------------------------------------------------------------------
Bug #3

Description of the bug:

	The condition of "if" statement should be "and" instead of "or".

Lines of source code that contain the bug:

	if ((firstNucleotide == input) || (secondNucleotide == input)) {

		return true;

	}

Lines of the fixed code:

	if ((firstNucleotide == input) && (secondNucleotide == input)) {

		return true;

	}

---------------------------------------------------------------------------
Bug #4

Description of the bug:

	The condition of while-loop is incorrect, which makes the iteration exit earlier than expected for certain inputs.

Lines of source code that contain the bug:

	while (index < sequence.length() - 1) {

		// The body of the while-loop.

	}

Lines of the fixed code:

	while (index < sequence.length()) {

		// The body of the while-loop.

	}

---------------------------------------------------------------------------